fix(browser): Use String() to stringify non-Error captureException inputs

`${exception}` throws a TypeError for Symbol inputs. Use String() instead,
which safely handles Symbols while producing identical output for all other
values. This was a pre-existing issue on the addExceptionTypeValue line.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: nicohrubec

packages/browser/src/eventbuilder.ts

@@ -334,8 +334,9 @@ export function eventFromUnknownInput(
   // - a plain Object
   //
   // So bail out and capture it as a simple message:
-  event = eventFromString(stackParser, `${exception}`, syntheticException, attachStacktrace);
-  addExceptionTypeValue(event, `${exception}`, undefined);
+  const stringifiedException = String(exception);
+  event = eventFromString(stackParser, stringifiedException, syntheticException, attachStacktrace);
+  addExceptionTypeValue(event, stringifiedException, undefined);
   addExceptionMechanism(event, {
     synthetic: true,
   });

packages/browser/test/eventbuilder.test.ts

@@ -182,6 +182,17 @@ describe('eventFromUnknownInput', () => {
     );
   });
 
+  it('does not throw and stringifies the value for a Symbol input', async () => {
+    const event = await eventFromUnknownInput(defaultStackParser, Symbol('foo'));
+
+    expect(event.exception?.values?.[0]).toEqual(
+      expect.objectContaining({
+        type: 'Error',
+        value: 'Symbol(foo)',
+      }),
+    );
+  });
+
   it('add a synthetic stack trace to DOMException with empty stack traces if attachStacktrace is true', async () => {
     const exception = new DOMException('The string did not match the expected pattern.', 'SyntaxError');
     exception.stack = '';